1. Field of the Invention
The present invention relates to a novel Eustoma having a deformed pistil, the stigma of which does not substantially open, and a method for breeding the same. More specifically, it relates to a novel Eustoma having a deformed pistil, the stigma of which does not open even after the flower perishes and has almost no possibility of being pollinated in a natural condition, thereby having an extremely good flowering period, and a method for breeding the same.
2. Description of the Related Art
Eustoma is a self-reproducing seed plant of Gentianaceae Eustoma, which is native to North America, and is well known as Toruko Gikyo in Japan. Presently, breeding of Eustoma for use as a cut flower or horticultural flower has been progressing, and plants having various colors and shapes are on the market. Such a Eustoma as a commercial product requires not only fineness of flower color or shape, but also preservation of freshness after shipment.
Generally, it is known that, after Eustoma come into flower, pollination accelerates aging of the flower and so the appreciation period becomes shorter. Thus, in order to frustrate pollination, refinements have been made, such as positioning an anther of a stamen lower than the position of a stigma so as to maintain a long flowering period.
Known techniques relating to Eustoma, include a method of producing a pure line Eustoma in a short time by using pseudofertilized ovule culture or hyperploidy pollen (Japanese Patent Application Laying-Open (Kokai) Nos. 2000-4701 and 2000-342093, a method of efficiently producing a Toruko Gikyo F1 hybrid by introduction of a male-sterile gene (Japanese Patent Application Laying-Open (Kokai) No. 9-107829, a method involving in efficient rooting by using callus culture (Japanese Patent Application Laying-Open (Kokai) No. 9-107831), and a method of efficiently producing a stunted Toruko Gikyo by adventitious embryo formation. (Japanese Patent Application Laying-Open (Kokai) No. 7-170870), but there are no reports regarding a deformed pistil or improvement in flowering period.
Method generally used to improve flowering period of a plant, include methods of controlling the outer environment of a plant, such as environmental management during distribution, or use of an agent. For example, there are known some devices and agents including a preserving device containing pressurized nonpolar gas (Japanese Patent Application Laying-Open (Kokai) No. 8-104601), a thermoregulated preserving device (Japanese Patent Application Laying-Open (Kokai) No. 10-150853), a buffer device for transporting flowers while carbon dioxide generates (Japanese Patent Application Laying-Open (Kokai) No. 2-242764), an agent for retaining the freshness of cut flowers (there exist many publications such as Japanese Patent Application Laying-Open (Kokai) Nos. 9-12401 and 8-198704), etc.
On the other hand, as a method for directly manipulating a plant itself, there has been attempted a method for improving flowering period by making a triploid plant or male-sterile plant, thereby controlling the reproductive function of the plant.
However, in general, high costs are required to control the outer environment and the effect has a certain limit. Moreover, there has been a problem that a triploid or male-sterile plant is poor in productivity because it cannot have a seed.